Motor-compressor unit for refrigerating apparatus



Nov. 24, 1936. A. A. MCCORMACK 2,062,035

MOTOR COMPRESSOR UNIT FOR REFRIGERATING APPARATUS Filed May 50, 1930 2Sheets-Sheet 1 HIHHH I I 71 i -7z 4-2.

26 O7fg' .1

(91w 1% M INVENTOR '33 I M i! ATTORNEY Patented Nov. 24, 1936 UNITEDSTATES PATENT OFFICE MOTOR-COMPRESSOR UNIT FOR REFRIGERATING APPARATUSApplication May 30, 1930, Serial No. 457,565

10 Claims. (01. 230-29) This invention relates to refrigeratingapparatus of the compression type and more particularly tomotor-compressor units for use with refrigerating apparatus of thecompression type.

Refrigerating apparatus of the compression type generally includes,among other elements, a compressor having its discharge side connectedto a condenser, and its intake side connected to an evaporator, theevaporator being in turn connected to the discharge side of thecondenser through some sort of pressure reducing means. Refrigeration isproduced by evaporating the liquid refrigerant under reduced pressure inthe evaporator, the vapors being compressed into and condensed in acondenser under a considerable higher pressure and subsequently fed backto the evaporator. In order to maintain the evaporator or therefrigerator cabinet, which generally houses the evaporator, at asubstantially constant temperature, it is customary to operate thecompressor intermittently. That is to say it is customary to start thecompressor when the temperature within the refrigerator reaches apredetermined high limit and to stop the compressor when the temperaturereaches a predetermined low limit.

Since the discharge side of the compressor is under condenser pressureand the suction side is under evaporator pressure, it is obvious thatthe compressor, whether of the reciprocating type,

the rotary type, the gyrator type or any other type, must start underload and consequently .the motor must have a high starting torque,unless some means is provided for allowing the motor to reach apredetermined speed before the load is taken up.

It is to such a means that my invention particularly relates, having forone of its objects means for loading and unloading the compressor,whereby when the compressor has been brought up to speed by its drivingmeans, it is automatically loaded and whereby when the speed of thecompressor drops below a predetermined limit, it is automaticallyunloaded. More specifically, it is an object of my invention to utilizethe lubricant within the system for operating the loading and unloadingof the compressor.

A further object of 'my invention is to provide in compressors whereincompression is accomplished by a member having a rotary pumping efiect,means whereby the compressing member may be moved by fluid pressure intooperative pumping relation with the cylinder, when the member is drivenat a predetermined speed by its driving member.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings? Fig. 1 is a view partly diagrammatic and partly invertical cross-section of an apparatus embodying features of thisinvention; and

Fig. 2 is a cross-sectional view taken on the line 2--2 of Fig. 1.

In order to illustrate my invention,,I have shown diagrammatically arefrigerating system having incorporated therein a motor-compressor unitof the hermetically sealed type. That is to say, a motor-compressor unitin which both the motor and the compressor are enclosed within ahermetically sealed casing, although it should be understood that myinvention is not limited to such a compressing unit.

For example in Fig. 1 I have shown a hermetically sealedmotor-compressor unit at I0 including a compressor. which is connectedto a condenser 2| through a conduit 22, a liquid refrigerant receiver 23connected to the discharge 25 side of the condenser 2|, and anevaporator 24. The refrigerant may flow in a closed path through theseparts in the order named. That is to say, the refrigerant is compressedin the compressor 20, forced through the conduit 22 into the condenser2| where it is liquefied, and finally collected in liquid form in theliquid receiver 23. From the liquid receiver 23, the liquid refrigerant1 passes through the conduit 25 into the evaporator 24, which, it shouldbe understood, is located within the cabinet or compartment to becooled. The refrigerant, evaporating within the evaporator 24, passes invapor form through the conduit 26 to the suction side of the compressor20, which will be described in more detail hereinafter. The

evaporator may be of any suitable type, and may be, for instance, of thefloat control valve type disclosed in the patent to Osborn, 1,556,708,patented October 13, 1925. The compressor 20 is shown as driven by anelectric motor 21, and the starting and stopping of the motor may bemade responsive to the temperature conditions within the evaporator. Tothis end, a pressure responsive snap switch 28 is connected to thesuction pipe 26 and this switch is located in the electric motor circuit29 to thereby start and stop the motor in accordance with refrigerantpressure conditions within the evaporator 24. The pressure conditionswithin the evaporator 24 Vary in proportion to the temperatureconditions within the evaporator, and consequently the switch 28 isresponsive to temperature conditions within the evaporator.

The motor-compressor unit indicated generally by the reference characterI8 is shown as consisting of an upper member 48, an intermediate member4| and a lower member '42, suitably held together with gaskets 43therebetween, by means of bolts, one of which is shown at 44. Theintermediate member 4| is provided with an inwardly extending portion 45forming a cylinder 46 for the compressor which compressor is hereinshown as of the gyrator type.

Mounted above the cylinder 46 is a motor 21, consisting of the stator 48secured .to the walls of the intermediate member 4|, and a rotor 49mounted on a shaft 58, which shaft 58 extends downwardly through thecylinder 46 into a bearing surface 41 formed in the lower member 42.Above the inwardly extending portion 45, is mounted a bearing surface 5|for the shaft 58 which bearing surface is flanged outwardly as at 52,the outwardly extending flange 52 resting on p and being secured to theinwardly extending portion 45 by means of bolts, one of which is shownat 53. The flange member 52 forms the upper surface of the cylinder 46.

The compressor includes a cylinder member and a piston member, and thesemembers are so constructed that they are in sealing arrangement when themotor reaches a predetermined speed but are not in sealing arrangementwhen the motor runs below this speed. This unloads the compressor duringthe starting period.

In this particular embodiment the compressor is of the gyrator type andis provided with a gyrator piston member 51 mounted on the eccentric 58formed integral with the shaft 58 of the motor. The gyrator pistonmember 51 is provided with an outwardly extending flange 68, whichflange is adapted to bear against the sur face 6| of the intermediatemember 45, when the gyrator is moved to its uppermost position by fluidpressure as hereinafter fully described. The compressor is provided witha discharge passage 62 discharging into the sealed casing |8, and with asuction or inlet passage extending through the inwardly extendingportion 45 as shown at 63.

In order to provide means for preventing a high starting torque or, inother words to provide means whereby a motor, having a low startingtorque may be used, I construct the gyrator piston member 51 in such amanner that it does not assume its sealed or operative pumping positionwithin the cylinder 46 until the eccentric 58 is driven at apredetermined speed. For example, I construct the gyrator in such amanner that it will remain spaced from the surfaces 52 and 6|, as shownin Fig. 1, until the speed of the motor reaches a predetermined highlimit, at which time it will be moved upwardly within the cylinder 46 toeffect compression. To this end, the gyrator 51 is mounted forlongitudinal movement upon the eccentric 58, and means in the form of anoil pump, operating in unisonwith the eccentric 58, is provided at thelower end of the motor shaft 58 for forcing oil or lubricant underpressure against the lower end of the gyrator 51 to cause the same tomove upwardly. For example as shown, an oil pump comprising the gears 69and 18, the gear 69 of which is mounted on the extension 1| of the motorshaft 58, discharges oil or lubricant under pressure through apassageway 12 to the circumferential ca ity 13, formed around theextension '1'.- From the cavity 13 the oil or lubricant flows throughthe radial passages 14 to the central passage 15 within the shaft 58,and thence into the lateral passage 16 to the offset chamber 11 belowthe gyrator 51.

The oil or lubricant for this purpose may be the oil or lubricant usedin the compressor and, as shown, is taken from the oil separator 18 fromwhere it flows downwardly through the passage 88 to the intake of theoil pump.

Thus it will be seen that, when the motor 21 and consequently the oilpump is operating at sufficient speed which may be predetermined, thatthe pressure exerted against the lower end of the gyrator 51 will causethe latter to be raised against the flange 52 and cause the outwardlyextending flange 68 to bear against the surface 6|, thereby bringing thegyrator or pump member .into pump relation with the cylinder 46.

The gyrator is further held in position for its pumping operation bymeans of the pressure generated within the sealed casing after thegyrator becomes operative. For example, the highrefrige erant pressurewithin the sealed casing may communicate through the passage I88 withthe cavity 98 below the flange of the gyrator. Thus the pressure of therefrigerant itself tends to hold the gyrator in its upper position inaddition to the lubricant pressure.

The operation of the device as a whole is as follows. Assuming that thecompressor is idle, then, as soon as the temperature within the evaporator 24 increases to the predetermined high temperature limit, thesnap switch 28 will start the motor 21. During the idle period thegyrator member 51 has assumed the position shown in Fig. 1 of thedrawings, that is, its unloaded position. The starting of the motor willrotate the shaft 58, causing the eccentric to revolve within the gyratormember. The movement of the eccentric within the gyrator will cause thesurface of the gyrator to move around the wall of the cylinder 46producing in efiect a rotary action. During the initial movement of themotor, the gyrator will not pump and consequentlythe motor starts underno load. As the motor speeds up, however, the oil pump 69, 18, speeds upuntil the pressure of the oil discharged by the oil pump is sufficientrator then begins its pumping operation and refrigerant and oil aredischarged under pressure through the passage to the oil separator 18.The refrigerant passesthough the motor casing and through the checkvalve I83 into the condenser where it is liquefied, finally collectingin liquid form in the receiver 23. From the receiver 23 the liquidrefrigerant passes to the evaporator 24 where it evaporates to produce acooling effect.

Should the speed of the motor decrease-or fall below a predeterminedminimum, or should the oil become depleted, the gyrator 51 will resumeits inoperative position and will be driven in an unloaded condition.

Thus I have disclosed apparatus for loading and unloading thecompressor, which, as shown above is dependent for its operation uponthe pressure of lubricant in the apparatus.

While the form of embodiment'of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the means for saidpumping member, fluid pressure means causing a relative movement of saidpumping member with respect to said casing other than the normalcompressing movement to thereby bring the pumping member into pumpingrelation with said "casing when the speed of the driving means reaches apredetermined high limit, and

driven by said driving means and means for loading the said member atthe predetermined high speed, said last named means including meansdependent upon said second pump for moving said pumping member relativeto said casing, to thereby bring said member in pumping relation withsaid casing.

3. A compressing unit comprising a casing, an eccentric mounted forrotary movement within said casing, driving means for said eccentric, agyrator pumping member mounted on said eccentric, and means formovingsaid gyrator member with respect to said casing in one direction whenthe eccentric is driven above a predeter- 'mined speed by the .drivingmeans to load said gyrator pumping member, and means for moving saidgyrator pumping member in the opposite direction to unload said gyratorpumping member when the eccentric is driven below a predetermined speed.

4. A compressing unit comprising a casing, a

- member having a rotary pumping effect mounted within said casing;driving means for said member, and means for unloading said member whenthe speed of said driving means is reduced below a predetermined limit,said last named means including means providing for relative movement ofsaid member and said casing to move said member out of pumping relationwith said casing, a second pump driven by said driving means, and

meansdependent upon said second pump for moving said member into pumpingrelation with said casing.

5. A compressing unit including a casing, an eccentric mounted forrotary movement in said casing, driving means for said eccentric, agyrator pumping member'mounted on said eccentric in means dependent uponsaid second pump for moving said member into pumping relation with saidcasing.

6. A compressing unit including a hermetically sealed casing, a motormounted within said casing, a cylinder within said casing, an eccentricdriven by said motor and mounted within said cylinder, 2. gyratorpumping member mounted on said eccentric, means for moving said pumpingmember into operative relation with said cylinder when the eccentric isdriven at a predetermined high speed, said last named means including anoil pump, said pump discharging oil under pres-' sure against the loweredge of said member.

7. A compressing unit comprising a casing; a pumping member within saidcasing, driving means for said pumping memberand fluid pressure meansfor causing relative movement of said pumping member with respect tosaid casing, to thereby bring said pumping member into pumping relationwith said casing when the speed of the driving means reaches apredetermined high limit, said last named means including an oil uponthe pressure created by said pump for aiding said fluid pressure meansin maintaining said pumping member in pumping relation.

8. A compressing unit comprising a,casing, an eccentric mounted in saidcasing, a motor, a shaft for said motor operatively connected tosaideccentric, a gyrator pumping member mounted on said eccentric withinsaid casing, and means for moving said gyrator into operative relationwith said casing, said last named means including an oil pump mounted onsaid shaft and means within said eccentric for delivering oil underpressure from said pump to said gyrator member.

9. A compressing'unit comprising a casing, a member having a rotarypumping eflect within said casing, means for loading. said member whenit is driven at a predetermined speed, said means including a body oflubricant within said casing, an oil pump communicating with saidbody-of lubricant and means for permitting said pump to dischargelubricant under pressure to said pumping member to thereby move saidmember into operative relation to-said casing.

10. A compressing unit comprising a casing, an eccentric mounted in saidcasing, a motor, a shaft for said motor operatively connected to saidec-= centric, a gyrator pumping member mounted on said eccentric withinsaid casing, said pumping member and said eccentriccooperating to forman operating chamber therebetween,-a second pump operatively connectedto said motor for discharging fluid into said operating chamber formoving said gyrator .pumping member into pumping relation when apredetermined speed of the motor is reached. I

ALEX. A. McCORMACK.

